Growth of MoS2 nanoflakes and the photoelectric response properties of MoS2/TiO2 NRs compositions

The initial reactant concentration and the substrate play an important role on the nucleation and growth of MoS2 nanostructures during hydrothermal growth. In this work, MoS2 nanoflakes are grown on FTO and TiO2 nanorod arrays (NRs) substrates. The morphology, optical and photoelectric properties of MoS2 nanoflakes are affected by the initial reactant concentration. Compared with the FTO substrate, MoS2 nanoflakes tend to grow on TiO2 NRs substrates due to less mismatch between TiO2 and MoS2. The large surface roughness and the presence of surface states of the TiO2 NRs facilitate the nucleation and growth of MoS2 nanoflakes. The photoelectric characteristics of MoS2/TiO2 NRs compositions have been investigated. The MoS2/TiO2 NRs compositions prepared using the initial reactant concentration with 4 mM S atom concentration exhibit the higher photoresponse behavior, which is attributed to the better heterojunction contact interface between MoS2 nanoflakes and TiO2 NRs. MoS2 nanoflakes can not completely cover the TiO2 NRs under low initial reactant concentration, resulting in the small area of the contact interface. On the other hand, MoS2 nanoflakes tend to form the self-assembly nanoflowers under high initial reactant concentration, which induces the carriers recombination in MoS2, the poor transport properties of MoS2 and the detrimental effects on the photogenerated current.